Stitch forming mechanisms for sewing machines



Nov. 1, 1960 T. J. ZYLBERT 2,958,300

STITCH FORMING MECHANISMS FOR SEWING MACHINES Filed Dec. 17, 1956 3 Sheets-Sheet 1 E IN V EN TOR. T lmddezos J Z ylbert Nov. 1, 1960 T. J. ZYLBERT s'rI'rcH FORMING MECHANISMS FOR SEWING MACHINES Filed Dec. 17, l56

3 Sheets-Sheet 2 Nov. 1, 1960 T. J. ZYLBERT smcn FORMING MECHANISMS FOR sswmc; MACHINES 3 Sheets-Sheet 3 Filed Dec. 17, 1956 INVENTOR. Thaddeus JZyZfiert BY j wzvze M ATTORNEY Unite States STITCH FORMING MECHANISMS FOR SEWING MACHINES Filed Dec. 17, 1956, Ser. No. 628,704

1 Claim. (Cl. 112192) The present invention relates to sewing machines and particularly to a loop-taker mechanism for lock-stitch sewing machines.

It is an object of this invention to provide in a lockstitch sewing machine a novel arrangement of the needle and cooperating loop-taker in which the bobbin is readily accessible and the stitching area is within convenient view of the operator.

In accordance with the present invention there has been combined in the construction of a sewing machine, a slanted needle bar which has the advantage that the point of stitch formation is forwardly relatively to the head of the machine, thereby increasing the operators visibility at the point of stitch formation, a laterally vibrating needle bar for effecting zigzag stitching, and a lock-stitch loop-taker, preferably an oscillating shuttle, which will properly cooperate with the needle having in mind the slanted needle bar and the lateral vibrations thereof, and at the same time, will provide a readily accessible bobbin.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a longitudinal elevational view, partly in section and partly in elevation, of a sewing machine embodying the present invention.

Fig. 2 is a head end view of the sewing machine of Fig. l, with the bed in section and the face plate removed.

Fig. 3 is a fragmentary sectional view taken substan tially on the line 33 of Fig. 1.

Fig. 4 is a bottom plan view of the bed of the machine of Fig. 1.

Fig 5 is a detail sectional view taken substantially on the line 5-5 of Fig. 2.

Fig. 6 is a detail sectional view taken substantially on the line 66 of Fig. 2.

With reference to the drawings the present invention is illustrated as embodied in a sewing machine having a frame comprising a bed 1, a standard 2 rising from one end of the bed 1 and carrying a bracket arm 3 that terminates in a head 4 overhanging the bed 1. The bed 1 includes a bed plate 5 the upper surface of which comprises the work supporting surface of the machine. At the point of stitch formation the bed plate 5 is provided with a throat plate 6 and extending from the throat plate to the front of the bed plate is a slide plate 7 that normally closes an access opening through the bed plate.

Journaled longitudinally of the bracket arm 3 in bearings 8 and 9 is a main shaft 10 which at the standard end thereof externally of the frame is provided with a combined hand wheel and belt pulley 11 having a belt atent O groove about which is entrained a belt 12 by means of which power is delivered to the main shaft 10 from a motor 13 mounted on the frame to the rear of the standard 2.

The presser mechanism of the machine is substantially the same as that disclosed and claimed in US. patent application of Johnson, Serial No, 471,766, filed November 29, 1954, now Patent No. 2,862,468, granted December 2, 1958. This mechanism includes a presser bar 14 mounted for sliding movement in a bushing 15 secured in a bore 16 in the bottom of the head 4 by a set screw 17 and carrying a presser foot 18 at its lower end. The presser bar is biased downwardly by a coil spring 19 arranged in an axial bore 20 in the presser bar and bearing at its lower end against the bottom of the bore 20 and at its upper end against the bottom of a plunger 21 slidably mounted in the bore 20. At its upper end the plunger 21 is provided with a pressure plate 22 having an annular groove 23 in the upper surface thereof. An abutment rod 24 is arranged parallel to and oifset rearwardly relatively to the presser bar 14 and has the lower end thereof engaged in the annular groove 23 in the plate 22. The rod 24 is mounted for axial sliding movement in a bore 25 in a bushing 26 which is in turn mounted in a bore 27 in a split lug 28 in the top of the head 4 and in which it is secured for oscillation by a screw 29. The bore 25 communicates directly with a threaded bore 30 in the upper part of the bushing 26, which bore 30 receives the threaded end 31 of an adjustment screw 32 bearing at its lower end against the top of the abutment rod 24 for adjustably holding the spring 19 under compression.

A needle bar 33 has a needle 34 secured to the lower end thereof by a needle clamp 35 which is the same as that disclosed and claimed in the above noted Johnson application Serial No. 471,766. The needle bar 33 is arranged upon an axis disposed at an acute angle of approximately eleven degrees relatively to a plane normal to the work supporting surface of the bed plate 5 and longitudinally of the bed. Thus, the needle at the point where it penetrates the throat plate 6 is disposed forwardly relatively to the head 4 so that the visibility of the operator at the point of stitch formation is not obstructed by the head 4. The presser bar 14 is disposed parallel to the needle bar.

The needle bar 33 is mounted for axial reciprocation in spaced bearing bores 36 and 37 formed in arms 38 and 39 respectively of a needle bar carrier or gate 40. The needle bar carrier 40 has an integral pivot stud 41 extending rearwardly from the arm 38 and normal to the axis of the needle bar 33. The stud 41 has a reduced end portion 42 and is journaled for oscillation in a bearing bushing 43 secured by a set screw 44 in a bore 45 in the bottom of the head 4. The stud 41 is held against axial movement by a screw 47 threaded into the end of the reduced end 42 of the stud and having a head 48 that engages against the outer end of the bushing 43. The stud 41 has an aperture 49 through which the presser bar 14 extends, which aperture 49 is enlarged with respect to the presser bar to provide for oscillation of the stud 41 relatively to the presser bar as the needle bar is vibrated laterally in zigzag stitching and for limited axial adjustment of the stud to adjust the position of the needle 34 relatively to the loop-taker.

Axial reciprocation is imparted to the needle bar 33 by a counterbalanced crank 50 mounted upon the end of the main shaft 10 within the head 4 having a crank pin 51 that is connected by a universal link 52 to an arm 53 on a collar 54 secured to the needle bar 33 by a set screw 55. The universal link 52, which is designed to accommodate the lateral vibration of the needle bar 33 in zigzag stitching, as shown, is the same as that dissite "faces of the body or frame portion 57 of the needle bar carrier 40.

Lateral vibration for performing zigzag stitching is imparted to the needle bar 33 by a link 58 having a bracket 59 secured to the end thereof by screws 60. The bracket 59 has a pair of lugs 61 having aligned'bores 62 receiving a coupling pin 63'that also passes through a pair -of lugs 64 and 65"integral with a gate 66in the form of a sleeve mounted for oscillation on the bushing 36 and held against axial movement thereon by ashoulder 67 (Fig. 3) on the bushing 26 and a collar 68se- Cured to the bushing 26 by a set screw 69. The coupling pin 63 is secured in the-lug 65 by a set screw 70. The specific means for imparting actuation to the" link 58 has not been shown since it forms no part of the present invention. Reference may be had to the above noted Johnson application, Serial No. 471,766 for a disclosure of one mechanism which could be used. At the side opposite from the lugs 64 and 65, the gate 66 is provided with a sleeve-like lug 71 having a bore 72 arranged normal to the axis of the gate 66. A siide 73 is mounted freely in the bore 72 in the lug 71 for'turning and for axial sliding movement and has an aperture 74 through which the needle bar 33 extends. The needle bar 33 passes through aligned apertures 75 in the annular walls of the lug 71 which are enlarged to provide for oscillation of the needle bar 33 about the axis of the stud 41 and for limited adjustment of the needle 34 relatively to the loop-taker. Thus, as the link 58 is actuated, the longitudinal movements thereof will oscillate the gate 66 which Will in turn, through the universal connection comprising the lug 71 and slide 73, transmit lateral motion to the upper end of the needle bar 73 and oscillate the same about the axis of the stud 41.

As noted in the Johnson application Serial No. 471,766, offsetting of the rod 24 relatively to the presser bar 14 and the use of the pressure plate 22. permits the desired spacing of the presser bar relatively to the needle bar 33 and, at the same time, provides adequate spacing between the rod 24 and bushing 26 upon which the gate 66 is pivotally mounted relatively to the needle bar 33 for the desired mechanical connection between the gate 66 and the needle bar 33. As more clearly seen in Fig. 5, the bore 25 in the lower end of the bushing 26 is eccentric toprovide for adjustment of the pivot axis of the gate 66 and thus for lateral adjustment of the neutral or center line position of the needle bar 33, it being apparent that upon rotation of the bushing '26, which is facilitated by a screw driver slot 76, the component of the motion of the gate 66 normal to the needle bar 33 will be taken up by sliding of the lug 71 relatively to the slide 73 while the lateral component will tilt the needle bar 33 about the axis of the pivot stud 41.

To advance the work across the bed plate 5, there is provided a feed dog 77 that cooperates with the presser foot 18. The feed dog 77 is mounted upon the end of a feed bar 78 pivotally mounted at its other end to a feed advance rocker 79 secured on a feed advance shaft 80 journaled longitudinally of the bed 1 by pintle bearings 81. A pitman 82 is connected at its lower end to a crank arm 83 secured to the shaft 80 and has a fork 84 at its upper end that embracesan eccentric 85 on the main shaft 10. Oscillation imparted to the pitman 82 by the eccentric 85 is converted to longitudinal reciprocation by a slide 86 carried by the pitman and cooperating with a guide-way 87 in an angularly adjustable block 88. Feed lift motions are imparted-to the The crank arm-89 is secured to a feed lift shaft 92 journaled longitudinally of the-bed 1 by pintle bearings 93. Oscillation is-imparted to the feed lift shaft 92 by a fork 94 integral with the shaft 92 and cooperating with a feed cam 95 on a bed shaft 96 journaled longitudinally of the bed 1 in pintle bearings 97. The bed shaft 96 is oscillated by a pitman 98 connected at its lower end to a crank arm 99 on thebed shaft and at its upper end to a crank 100 on the main-shaft 10. The feeding mechanism advances the work transversely or front to back of the bed plate 5 and thereby defines a normal line of feed that is transverse to the plane defined by the lateral vibration of the needle bar 33.

Cooperating with the needle 34 in the formation of stitches is a circularly moving loop-taker mechanism comprising preferably an oscillating shuttle 101 having a loop-seizing beak 102, which shuttle is joumaled in an open-sided raceway 103 in a shuttle body 104 for oscillation in a plane transversely of the line of feed and parallel to the plane of motion of the needle bar 33. The construction and operation of the shuttle 101 are conventional and it is not believed that any detailed disclosure thereof is necessary. The open'side of the shuttle raceway 103 is closed by a so-called snap-out shuttle cap 105 having a rearwardly extending arm 106 that is hinged to the shuttle body by a resiliently mounted hinge pin 107 such as disclosed in the Johnson Patent No. 2,761,402. The shuttle cap 105 is held inits normal operative position by a pair of resiliently mounted swing-out latches 108 pivotally mounted on the shuttle body 104 by screws 109. The shuttle cap 105 is provided with a notch 110 that receives a rotation restraining finger 111 of a bobbin case 112 carried by the shuttle 101. Oscillation is imparted to the shuttle 101 by a shuttle driver 113 mounted upon the end of a shuttle actuating shaft 114 journaled for oscillation in the shuttle body 104 which also includes an enlarged internal cavity 115 defining a gear case which accommodates a bevel gear 116 on the shaft 114 which bevel gear'cooperates with a similar gear 117 on the end of a shuttle shaft 118' journaled longitudinally of the bed 1 in bear ing lugs 119 and 120 and extending into the cavity 115. The shuttle body itself is secured to the lug 120 by screws 121. The shuttle shaft 118 is oscillated by a fork 122 integral with the bed shaft 96 and cooperating with a slide 123 carried by a crank arm 124 mounted on the shaft 118.

Normally, in sewing machines of the type herein disclosed, the bobbin which is carried by the bobbin case 112 is replaced when the thread supply is exhausted by removing the bobbin case 112 from the shuttle, with a slide plate as at 7 providing access to the bobbin case. In accordance with the present invention there has been provided means whereby the bobbin case is readily accessible through the aperture in the bed plate 5 provided by'the slide'plate 7. Toward this end, the shuttle 101 is preferably arranged upon an inclined axis disposed at substantially an angle of eleven degrees to the horizontal. When the shuttle is thus tilted upwardly, it is a relatively simple matter to remove the bobbin case through the opening provided by the slide plate 7. At the same time, the normal cooperation of the shuttle 101 with the needle 34 at loop seizure requires that the needle operate in a plane that is closely adjacent to the. plane defined by the motion of the loop seizing beak102 ofthe shuttle. ln particular, in a zigzag sewing machine, the lateral vibrations of the needle bar should be in a plane preferably parallel and closely adjacent to the plane of motion of the loop seizing beak. Thus, the shuttle axis should'be substantially normal to the plane of motion of the needle bar, andsince the shuttle is arranged at an angle of eleven degrees to the horizontal, the needle bar 33, while .still being mounted in an optimum manner relatively to the shuttle 101, can be arrangedat an acute angle of eleven degrees to the vertical, which increases the visibility at the point of stitch formation by placing'the point of stitch formation forward relatively to the head 4. Consequently, arranging the shuttle upon an inclined axis not only increases accessibility of the bobbin, but also permits a desirable needle bar arrangement.

With the shuttle 101 on an inclined axis, it will be apparent that the shuttle cap 105, if pivoted at a point in the plane of the cap, upon being swung out, would contact the under side of the slide plate 7 and would, in general, define a wide swing-out are that would require that it be swung out a considerable distance before the shuttle 101 could be removed and would be difficult to manipulate through the aperture provided by the slide plate 7. This disadvantage has been overcome by providing a pivot that is located to one side of and behind the shuttle cap and by use of the arm 106 of the cap. Thus, the pivot pin 107 can be located in a vertical plane below and to one side of the uppermost part of the shuttle cap 105, so that the cap 105 will begin to drop immediately as it is swung out and it will fall away very fast downwardly and to the one side, requiring less motion of the cap to free the shuttle 101 and at the same time, the motion of the cap will be in the range that is readily accessible through the slide plate opening in the bed plate 5. Pivoting the shuttle cap 105 to the side also affords a manufacturing advantage. To provide clearance in the shuttle body 104 to receive the arm 106 and thus locate the pivot pin 107 behind the front face of the shuttle body, it is necessary only to slab the one corner of the shuttle body 104 as shown at 125. Such a construction is not only considerably simpler than would be required with the pivot disposed vertically below the axis of the shuttle but also reduces the required depth of the bed mechanism.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claim.

Having thus set forth the nature of the invention, what I claim herein is:

In a sewing machine having a frame including a bed having a work-supporting surface and a bracket arm terminating in a head overhanging said work-supporting surface, feeding mechanism mounted in said bed for advancing work across said work-supporting surface and defining a line of feed, a needle bar mounted in said head for axial reciprocation on an axis inclined at an acute angle to a plane normal to said work-supporting surface and transverse to the line of feed, a needle carried by said needle bar, a lock-stitch loop-taker mounted in said bed for cooperation with said needle in the formation of stitches and having a replaceable bobbin mounted therein, said work-supporting surface having an opening adjacent said loop-taker to provide access to said bobbin and a plate for normally closing said opening, said looptaker being journaled in said bed for angular movement about an axis normal to a plane including the axis of said needle bar and transverse to the line of feed.

References Cited in the file of this patent UNITED STATES PATENTS 467,299 Neely Jan. 19, 1892 1,155,051 Eames Sept. 28, 1915 1,378,677 Hemleb May 17, 1921 1,469,066 Bell et al Sept. 25, 1923 2,394,510 Clayton Feb. 5, 1946 2,662,495 Parry Dec. 15, 1953 2,713,838 Johnson et a1. July 26, 1955 

